Pen-based computer systems operate according to a simple "pen metaphor" that allows a user to enter data by using a pen to "write" directly on the display device of the pen-based computer. The pen may be a light pen or a device shaped like a pen that facilitates data entry on a position-sensitive display device. The process of entering data for pen-based computers is often called "inking," and the data entered by inking is typically known as "ink data."
Pen-based computers provide the user with a simple mechanism for entering data quickly without the requirement that the user be a proficient typist. The ink data may be transcribed at a later time using "recognition" software that "recognizes" handwritten characters and translates them into a desired font or ASCII characters. Unrecognized ink data are typically treated as graphical objects rather than as text. Because much of the pen-based application software supports inking, a keyboard is not required for data entry. Thus, the total size of a pen-based computer can be greatly reduced when compared to a computer system having a keyboard for an input device.
Not all software that is executed by a pen-based computer system necessarily supports inking. For example, the operating system of the pen-based computer may not support inking. One solution to this problem is the On-Screen Typewriter sold by Microsoft.RTM. Corporation as part of the Pen Windows.RTM. software package. The On-Screen Typewriter provides the user with a graphical representation of a typewriter that allows the user to "type" data into the currently selected application or "active" window. The user types in data by selecting the desired characters using the light pen. This process is slow and cumbersome and destroys many of the advantages of the pen metaphor.
An additional problem that may be encountered by the user of a pen-based computer is that some application programs use higher quality recognition programs than other application programs. For example, some application programs allow "deferred" recognition, while other applications perform recognition immediately. The recognition process can interrupt the process of inking, forcing the user to wait for recognition to occur before continuing to "write" the next word. Deferred recognition is therefore preferable because it allows the user to "write" without interruption and to recognize the ink data when convenient. Further, some recognition programs are "destructive" in that the ink data objects cannot be recovered once they have been recognized, wherein other recognition programs are "non-destructive" and allow the recovery of the ink data objects after they have been recognized. Non-destructive recognition programs are typically preferable.
A further difficulty encountered by the user of pen-based computers is that ink data is often difficult to export to another application program. When inking, a pause in the movement of the light pen or the lifting of the light pen from the display device can cause a separate ink data structure to be created. Thus, a single sentence or a single word may consist of several data structures. For some application programs such as Microsoft Notebook, only one data structure may be exported at a time using a "cut-and-paste" export method. For example, a user inks the word "notes" in a document using an application program that supports deferred recognition of the ink data. At a later time, the user desires to export the contents of the inked document to a word processor program that does not support inking. To export the word "notes," the user first selects the word "notes" for transcription into text. When the user attempts to select the entire word "notes," he discovers that the application program has divided the word "notes" into two distinct objects, one including the letters "no," and the other including the letters "tes." Each letter grouping typically must undergo the recognition process separately. After recognition, the letter groupings remain separate objects, and typically there is no mechanism for grouping several transcribed text objects into a single object. Thus, the user must select one letter grouping, perform a "copy" operation, leave the application program, select the word processor, and "paste" the object into the target document. The "copy-and-paste" process is repeated for each object, which can be a time-consuming process.